“Everyone knows that you shouldn’t eat junk food and you should exercise,” says Kelly D. Brownell, the director of the Rudd Center for Food Policy and Obesity at Yale. “But the environment makes it so difficult that fewer people can do these things, and then you have a public health catastrophe.”

So what to make of Kelly Brownell’s complaint about the unhealthy food environment? Let’s use a case study: Kelly Brownell.

Brownell would seem to be in an ideal “food environment.” As a Yale University professor, he’s surely pulling in a six-figure salary, which means he can buy all the healthy foods that are supposedly too expensive for the Average Joe. (Brownell can even afford to go “organic” and “heirloom” if he wants to.) His job involves repeatedly demonizing whole categories of food and thinking of ways to get people not to consume them—like arguing that the tax code should be used to nudge everybody in the “correct” direction. His co-workers at Yale’s Rudd Center for Food Policy are presumably like-minded, and probably equally vigilant, about avoiding a “bad food environment.”

[Brownell] sports a good-size paunch thanks, he says, to a book project that has kept him relatively sedentary and snack-prone for the last year or so. In photographs taken a few years back, Kelly Brownell looks much trimmer.

Some obesity activists like to act as if our environment has spiraled out the individual control of consumers, that we’re almost helpless in the face of the abundant choices we have. But isn’t our “environment” the result of choices we make for ourselves? In the debate over fitness (and fatness), it’s sometimes easy to forget who’s really in control.